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Sum of series 2i+1/n



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The solution

You have entered [src]
  oo           
 ___           
 \  `          
  \   /      1\
   )  |2*i + -|
  /   \      n/
 /__,          
i = 1          
i=1(2i+1n)\sum_{i=1}^{\infty} \left(2 i + \frac{1}{n}\right)
Sum(2*i + 1/n, (i, 1, oo))
The radius of convergence of the power series
Given number:
2i+1n2 i + \frac{1}{n}
It is a series of species
ai(cxx0)dia_{i} \left(c x - x_{0}\right)^{d i}
- power series.
The radius of convergence of a power series can be calculated by the formula:
Rd=x0+limiaiai+1cR^{d} = \frac{x_{0} + \lim_{i \to \infty} \left|{\frac{a_{i}}{a_{i + 1}}}\right|}{c}
In this case
ai=2i+1na_{i} = 2 i + \frac{1}{n}
and
x0=0x_{0} = 0
,
d=0d = 0
,
c=1c = 1
then
1=limi2i+1n2i+2+1n1 = \lim_{i \to \infty} \left|{\frac{2 i + \frac{1}{n}}{2 i + 2 + \frac{1}{n}}}\right|
Let's take the limit
we find
True

False
The answer [src]
     oo
oo + --
     n 
+n\infty + \frac{\infty}{n}
oo + oo/n

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